To the Editor.—In the September 4, 1987, issue of JAMA, Drs Wyllie, Pippenger, and Rothner1 clearly pointed out that in the patient they studied, the bioavailability of a generic preparation of primidone was inadequate in achieving potentially protective blood levels at the time the patient was studied. In your thoughtful editorial appearing in the May 5, 1989, issue of JAMA2 that critical point is not acknowledged or addressed. It is, however, the central point of the above-mentioned article by Wyllie et al.Clearly, in the patient presented by our colleagues, the bioavailability of generic primidone and its derivatives to the patient they reported was inadequate as reflected by blood levels. To say that the patient went on, with a nongeneric drug, to have seizures at some further point in time neither addresses nor excuses the inadequacy of bioavailabilty of potentially protective pharmacologic agents at the time the